JPH0983984A - Bi-directional amplifier for catv - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce upstream merging noise from a terminal by providing the distributor or the branch device of a downstream signals and the downstream exclusive terminal so as to output one of the downstream signal outputted from the distributor or the branch device to a downstream side terminal and the other to the downstream exclusive terminal. SOLUTION: A distributor distributing into two 8 is provided between an amplifier part 5 and a second branch filter 4 and the downstream exclusive terminal 7 outputting the downstream signal is provided to one output side of the distributer 8. In this amplifier, the downstream signal inputted to a upstream side terminal 1 is amplified by a downstream amplifier part 5 through the high-pass filter of a first branching filter 3 and distributed by the distributor distributing into two 8. As one downstream signal of them is outputted the downstream side terminal 2 through the high-pass filter of the second branching filter 4 and the other downstream signal is outputted to the downstream exclusive terminal 7, a downstream signal can be received by connecting the receiving equipment of the terminal side to the exclusive terminal 7. In this case, noise from the receiving equipment is prohibited from flowing to the upstream side by the second branch filter 4.

Description

Detailed Description of the Invention

[0001]

The bidirectional amplifier for CATV of the present invention is used in a bidirectional CATV system.

[0002]

2. Description of the Related Art Conventionally, there is a bidirectional amplifier used in a bidirectional CATV system as shown in FIG.
This is because the downstream signal input to the upstream terminal A and the upstream signal input to the downstream terminal B have a first demultiplexing filter D and a second demultiplexing filter E provided between both terminals A and B. Is amplified by the respective amplification units F and G provided between the two demultiplexing filters D and E, and after amplification, the downstream side terminal B and the upstream side terminal A are passed through the both demultiplexing filters D and E. It is designed to be output from each of.

[0003]

However, the above-mentioned CA
The bidirectional amplifier for TV has the following problems. Since the terminal for outputting the downlink signal and the terminal for inputting the uplink signal are the common downstream side terminal B, it is possible to use a TV receiver or a home terminal in the subscriber's house (not shown) connected after the downstream side terminal B. The generated noise is input to the upstream amplification section F together with the upstream signal through the downstream terminal B and is amplified,
Further, it is output from the upstream terminal A and transmitted to the center side. Similarly, if noise from each subscriber's house is transmitted to the center side, it becomes a large ingress noise, and C /
N is significantly deteriorated.

It is an object of the present invention to carry out bidirectional communication as before, and further reduce the upstream and downstream noise from terminals.
It is to provide a bidirectional amplifier for TV.

[0005]

As shown in FIG. 1, a CATV bidirectional amplifier according to the present invention uses a downstream amplifier 5 for transmitting a downstream signal input to an upstream terminal 1 through a first demultiplexing filter 3.
Thus, in a CATV bidirectional amplifier capable of amplifying and transmitting the upstream signal input to the downstream terminal 2 through the second demultiplexing filter 4 by the upstream amplification unit 6, the downstream signal is increased to 2 or more in the same amplifier. A distribution or branching unit 8 for distributing or branching and outputting and a downlink dedicated terminal 7 are provided, and one of the downlink signals output from the distribution or branching unit 8 is the downstream side terminal 2.
On the other hand, the other is configured to be output to the downlink dedicated terminal 7, respectively.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a bidirectional amplifier for CATV of the present invention will be described with reference to FIG. The upstream side terminal 1 of this amplifier is a transmission line (coaxial cable) on the center side.
Is connected, and the down signal from the center is input and the up signal from the terminal side amplified by the amplifier is output. The downstream side terminal 2 is connected to a transmission line (coaxial cable) on the terminal side, to which an upstream signal from the terminal side is input and a downstream signal amplified by an amplifier is output.

The amplifier is provided with a first demultiplexing filter 3 connected to the upstream terminal 1 and a second demultiplexing filter 4 connected to the downstream terminal 2. The first and second duplex filters 3 and 4 each include a high-pass filter and a low-pass filter. The high-pass filter allows passage of the transmission frequency band of the downstream signal, and the low-pass filter transmits the upstream signal. It allows the frequency band to pass. Therefore, for example, when the transmission band of the downstream signal is 76 to 750 MHz and the transmission band of the upstream signal is 10 to 50 MHz, the high-pass filter is a filter that allows passage of 76 MHz or more, and the low-pass filter passes 50 MHz or less. It is a filter that enables it.

Further, this amplifier is provided with a downlink amplification section 5 which is connected to the high-pass filter of the first demultiplexing filter 3 and the high-pass filter of the second demultiplexing filter 4 and amplifies the downstream signal. An upstream amplification unit 6 that is connected to the low-pass filter of the wave filter 3 and the low-pass filter of the second demultiplexing filter 4 and amplifies the upstream signal is provided. Power is supplied from an AVR (power supply circuit) 9 to both the amplifiers 5 and 6, and the AVR 9 separates the AC power superimposed on the coaxial cable from the signal line, transforms it, rectifies it, and outputs it to a predetermined level. DC is generated.
This amplifier is also provided with a power supply separation filter including a capacitor D and a coil H for separating the power superimposed on the signal. The AVR 9 can also operate at AC 100V.

Two dividers (dividers or dividers) 8 are provided between the amplification section 5 and the second demultiplexing filter 4.
A dedicated downlink terminal 7 for outputting a downstream signal is provided on one output side of the distributor 8.

In this amplifier, the downstream signal input to the upstream side terminal 1 is amplified by the downstream amplification section 5 through the high pass filter of the first demultiplexing filter 3 and divided into two by the two divider 8. One of the downlink signals is output to the downstream terminal 2 through the high pass filter of the second demultiplexing filter 4, and the other downlink signal is output to the downlink dedicated terminal 7. Therefore, the terminal 7 is connected to the terminal side receiving device. Can be connected to receive a downlink signal. The upstream signal input to the downstream side terminal 2 is amplified by the upstream amplification unit 6 through the low pass filter of the second demultiplexing filter 4, and the amplified upstream signal is passed through the low pass filter of the first demultiplexing filter 3 and upstream. Output from terminal 1.

[0011]

When the bidirectional amplifier for CATV of the present invention is used in a bidirectional CATV system, bidirectional transmission is possible as in the conventional case and the following effects are obtained. That is, if a receiving device on the terminal side is connected to the downlink dedicated terminal, the receiver can receive the downlink signal, and noise from those devices is blocked by the second demultiplexing filter and does not flow to the upstream side. Therefore, upstream combined noise is reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a CATV bidirectional amplifier according to the present invention.

FIG. 2 is a block diagram showing an example of a conventional bidirectional amplifier for CATV.

[Explanation of symbols]

 1 Upstream-side terminal 2 Downstream-side terminal 3 First demultiplexing filter 4 Second demultiplexing filter 5 Downlink amplification section 6 Upstream amplification section 7 Downlink dedicated terminal 8 Distribution or branching device

Claims (1)

[Claims] 1. A downstream signal input to an upstream terminal (1) is passed through a first demultiplexing filter (3) by a downstream amplifier (5) to a second upstream signal input to a downstream terminal (2). A bidirectional amplifier for CATV that is capable of being amplified and transmitted by an upstream amplification section (6) through a wave filter (4), and a distribution or branching device that distributes or branches a downstream signal into two or more and outputs the same to the amplifier. 8) and a downlink dedicated terminal (7) are provided, one of the downlink signals output from the distributor or the branching device (8) is output to the downstream side terminal (2), and the other is output to the downlink dedicated terminal (7). A bidirectional amplifier for CATV, which is characterized in that